1. Field of the Invention
This invention relates to an apparatus and a method for producing a harness, which include a treatment of stripping the cover on an intermediate area of a wire as well as a treatment of working an end of the wire.
2. Statement of the Prior Art
In a harness for a motorcar, the cover on a wire is stripped off at an intermediate area to connect a branch wire to the intermediate area.
Heretofore, such harness has been produced by stripping the cover of the wire at an intermediate area by using a wire stripper or the like by hand after the wire had been worked at the end by a single purpose machine.
For convenience of explanation, a prior harness producing apparatus will be described below by referring to FIGS. 18 to 20.
FIGS. 18 and 19 are side views of a conventional harness producing apparatus, which illustrate operations of the apparatus. FIG. 20 is a schematic side view of another conventional harness producing apparatus.
A prior harness producing apparatus A, as shown in, for example, FIG. 18, is provided along a passing line of a wire 10 with, in order, a pair of feed rollers 11, a pair of draw rollers 12a, a front side clamp 12, a cutter assembly 13, and a rear side clamp 14. The wire is held between both clamps 12 and 14 while the cutter assembly 13 is closed in synchronization with the clamping of the wire by the clamps 12 and 14. Then, a pair of central cutting-off cutters 13a in the cutter assembly 13 cut off the wire 10, while two pairs of cutting-into cutters 13b in opposite sides of the cutter assembly 13 cut into the outer cover of the wire 10. The front side clamp 12 moves in the direction shown by the arrow Q while the cutters 13b cut into the cover, thereby stripping the cover on the end of the wire 10 which is held in the front side clamp 12 (hereinafter referred to as the remaining wire 10). In connection with this stripping process, the rear side clamp 14 moves in the direction shown by the arrow P, thereby stripping the cover on the end of the wire 10 which is held in the rear side clamp 14 (hereinafter referred to as the cut-off wire 10).
Then, the remaining wire 10 together with the front side clamp 12 is moved in a direction perpendicular to the paper surface of FIG. 18 and a terminal 2 (see FIG. 19) is pressed on the stripped end of the remaining wire 10 by a terminal-pressing machine (not shown). After pressing the terminal, the front side clamp 12 is returned to the original position.
Meanwhile, the rear clamp 14 is moved in a direction perpendicular to the paper surface of FIG. 18 and a terminal (not shown) is pressed on the stripped end of the cut-off wire 10 by a terminal-pressing machine (not shown). Then the clamp 14 releases the cut-off wire 10 at a given discharge position and is returned to the original position.
As shown in FIG. 19, when both clamps 12 and 14 are open and the pair of feed rollers 11 are driven so that the wire is fed toward the draw rollers 12a, the draw rollers 12a are driven with a slight time lag after feeding the wire so that the wire 10 is fed toward the rear side clamp 14 as shown in FIG. 18.
The covers on the opposite ends of the wire are stripped and the cut-off wire (harness) with the terminals 2 pressed on the opposite stripped ends are successively produced by repeating the above processes.
A plurality of the harnesses thus produced are bundled and transferred to the next step. Then, as described above, the harness is stripped at the intermediate area by hand.
In such a harness producing method, however, since the stripping treatment at the intermediate area is effected by hand, the precision of stripping is scattered due to different spersonal abilities and thus it is difficult to stabilize the quality of the harness. Further, an additional step of transferring the wire is necessary to carry a bundle of the harnesses produced by the apparatus A to the next step. This results in an increase in the number of steps.
Accordingly, it has been desired to automatically effect a series of working operations from the wire-end treatment to the stripping treatment at the intermediate area in order to overcome the above problems. As shown in FIG. 20, it has been first proposed to form a unit C by combining the above harness producing apparatus A with an existing stripping apparatus B.
In this unit C, after the wire 10 is set in the stripping apparatus B and in the harness producing apparatus A, the apparatuses A and B are driven. The wire 10 is cut off, the covers on the opposite ends of the cut-off wire are stripped and the terminals are pressed on the stripped ends in unit C.
Then, the feed rollers are driven so that the wire 10 is fed in wire-feeding direction P by a given length. One end of an intermediate area of the wire 10 to be stripped is positioned in opposition to the top of the cutters 21 in the stripping apparatus B. After the wire 10 is held in a clamp 20 in the stripping apparatus B, the cutters 21 are closed so that the cutters 21 cut into the outer cover of the wire 10. Then the cutters 21 are moved along the wire 10 to the other end of the intermediate area to be stripped while the cutters 21 cut into the cover. The cover at the one end of the intermediate area is cut away from the remaining cover and compressed toward the other end of the intermediate area, thereby stripping the cover at the intermediate area.
After the clamp 20 releases the wire 10, the feed rollers 11 and the draw rollers 12a are driven so that the wire 10 is fed along direction P toward the cutter assembly 13. At this time, the length of the cut-off wire (harness) corresponds to the sum of the feeding distances of the wire before and after stripping the intermediate area. Accordingly, the position on the wire 10 to be cut off next is set in opposition to the top of the cutters 13a.
Thus, one cycle is completed. Harnesses stripped at the intermediate area are successively produced by repeating the above processes.
Unit C can automatically carry out a series of working processes from the end treatment, such as the cutting-off treatment, end-stripping treatment, terminal-pressing treatment and the like, to the intermediate stripping treatment, thereby stabilizing the quality of the harness, eliminating the wire-transferring process between the end treatment and the intermediate treatment, and reducing the number of steps.
In unit C, however, since the wire is positioned by driving the feed rollers 11 during the intermediate stripping treatment and the cutting-off treatment in one cycle, the feed rollers 11 should be driven twice in one cycle. In general, it is necessary to set a given rest period from the time immediately after the feed rollers (and the draw rollers 12a) are stopped to the time when the next treatment is started. Accordingly, if the number of times of feeding and resting the feed rollers 11 increase, the rest period is correspondingly elongated, the period for a cycle becomes longer, and it is difficult to efficiently produce the harness.